Inhibition of Rho kinase modulates radiation induced fibrogenic phenotype in intestinal smooth muscle cells through alteration of the cytoskeleton and connective tissue growth factor expression

BACKGROUND

Late radiation enteritis in humans is associated with accumulation of extracellular matrix and increased connective tissue growth factor (CTGF) expression that may involve intestinal muscular layers.

AIMS

We investigated the molecular pathways involved in maintenance of radiation induced fibrosis by gene profiling and postulated that alteration of the Rho pathway could be associated with radiation induced fibrogenic signals and CTGF sustained expression.

PATIENTS AND METHODS

Ileal biopsies from individuals with and without radiation enteritis were analysed by cDNA array, and primary cultures of intestinal smooth muscle cells were established. Then, the effect of pharmacological inhibition of p160 Rho kinase, using Y-27632, was studied by real time reverse transcription-polymerase chain reaction, western blot, and electrophoretic mobility shift assay.

RESULTS

Molecular profile analysis of late radiation enteritis showed alterations in expression of genes coding for the Rho proteins. To investigate further the involvement of the Rho pathway in intestinal radiation induced fibrosis, primary intestinal smooth muscle cells were isolated from radiation enteritis. They retained their fibrogenic differentiation in vitro, exhibited a typical cytoskeletal network, a high constitutive CTGF level, increased collagen secretory capacity, and altered expression of genes coding for the Rho family. Rho kinase blockade induced a simultaneous decrease in the number of actin stress fibres, alpha smooth muscle actin, and heat shock protein 27 levels. It also decreased CTGF levels, probably through nuclear factor kappaB inhibition, and caused decreased expression of the type I collagen gene.

CONCLUSION

This study is the first showing involvement of the Rho/Rho kinase pathway in radiation fibrosis and intestinal smooth muscle cell fibrogenic differentiation. It suggests that specific inhibition of Rho kinase may be a promising approach for the development of antifibrotic therapies.

Regulation of the collagen phenotype expression of gamma-irradiated vascular smooth muscle cells by heparan mimetics (RGTA)

Restenosis is characterized by vascular smooth muscle cell (VSMC) proliferation and accumulation of collagen III in a hypertrophic and disorganized extracellular matrix. Restenosis is prevented by antimitotic agents or irradiation but no significant progress has been made to control collagen expression deregulation. Previously, we have shown that a new family of biopolymers named RGTA (heparan mimetics elaborated by grafting on dextran of carboxylate, sulfate, and benzylamide units) stimulate in vivo tissue repair and reduce fibrosis in various models. Using VSMC in vitro (pig aortic VSMC irradiated with a 60Co source and labeled with [3H]Proline), we now show that gamma-irradiation reduced cell survival by 50% and collagen synthesis 6-fold with a major increase in the ratio of collagen III to collagen I biosynthesis taken as a fibrotic index. RGTA added to the cells enhanced their survival up to 80% and reduced collagen III/I ratio back to values found in normal vascular tissues. These results suggest that RGTA combined with gamma-radiation could be an efficient strategy against restenosis.

Heparan mimetic regulates collagen expression and TGF-beta1 distribution in gamma-irradiated human intestinal smooth muscle cells

Radiation-induced intestinal fibrosis is characterized by collagen accumulation, a process in which TGF-beta1 plays a key role. We analyzed the effects of gamma radiation on collagen expression and TGF-beta1 distribution in human intestinal smooth muscle cells (HISM). We investigated the activity of a carboxymethylated and sulfated dextran (RG-1503), exhibiting antifibrotic properties and promoting in vivo intestinal tissue repair, on irradiated HISM. After (60)Co irradiation (10 Gy), HISM were labeled with [(3)H] proline (+/-RG-1503). Radiolabeled collagen I, III, and V were quantified by SDS-PAGE. TGF-beta1 was quantified by ELISA in culture medium, pericellular and intracellular compartments. Irradiation induced a specific 2.85-fold increase in collagen III production by HISM. Collagen V decreased by 80% 72 h after irradiation. Pericellular TGF-beta1 was increased (up to twofold) in irradiated HISM. RG-1503 added before or after irradiation reversed both mRNA and protein levels of collagen III and V to control values. RG-1503 decreased the amount of TGF-beta1 in the cell layer below the control values. Irradiation of HISM induced the development of a fibrotic phenotype in terms of collagen production and TGF-beta1 distribution. The antifibrotic RG-1503 restored HISM physiological characteristics and may represent a promising therapeutic approach for radiation-induced intestinal fibrosis.

Autosomal dominant type IIa hypercholesterolemia: evaluation of the respective contributions of LDLR and APOB gene defects as well as a third major group of defects

Autosomal dominant type IIa hypercholesterolaemia (ADH) is characterised by an elevation of total plasma cholesterol associated with increased LDL particles. Numerous different molecular defects have been identified in the LDL receptor (LDLR) and few specific mutations in the apolipoprotein B (APOB) gene resulting in familial hypercholesterolaemia and familial defective apoB-100 respectively. To estimate the respective contribution of LDLR, APOB and other gene defects in this disease, we studied 33 well characterised French families diagnosed over at least three generations with ADH through the candidate gene approach. An estimation of the proportions performed with the HOMOG3R program showed that an LDLR gene defect was involved in approximately 50% of the families (P = 0.001). On the other hand, the estimated contribution of an APOB gene defect was only 15%. This low estimation of ADH due to an APOB gene defect is further strengthened by the existence of only two probands carrying the APOB (R3500Q) mutation in the sample. More importantly and surprisingly, 35% of the families in the sample were estimated to be linked to neither LDLR nor APOB genes. These data were confirmed by the exclusion of both genes through direct haplotyping in three families. Our results demonstrate that the relative contributions of LDLR and APOB gene defects to the disease are very different. Furthermore, our results also show that genetic heterogeneity is, generally, underestimated in ADH, and that at least three major groups of defects are involved. At this point, the contribution of the recently mapped FH3 gene to ADH cannot be assessed nor its importance in the group of 'non LDLR/non APOB' families.

Catabolism of HDL1 cholesteryl ester in the rat. Effect of ethinyl estradiol treatment

The present study was performed in control and ethinyl estradiol-treated rats in order to determine the mechanisms involved in the catabolism of HDL1 cholesteryl ester. Ligand blottings on liver membranes showed that purified HDL1, containing about 70% apolipoprotein E and 10% apolipoprotein AI, bind to the LDL receptor (130 kDa) and not to HB2 (100 kDa) or SR-BI (82 kDa), candidate HDL receptors. Immunoblots showed that the treatment increased the hepatic level of the LDL receptor five- to ten-fold, strongly decreased that of SRBI and did not change that of HB2. An in vivo kinetic study showed that the turnover of HDL1 cholesteryl ester is more rapid in treated than control rats. The liver participation (60%) in this clearance was not modified by the treatment. Therefore, it can be concluded that the catabolism of HDL1 cholesteryl ester, in control as in treated rats, is essentially ensured by the uptake of entire particles in the hepatocytes via LDL receptors.

Ionizing radiation alters hepatic cholesterol metabolism and plasma lipoproteins in Syrian hamster

PURPOSE

The investigation of the effects of ionizing radiation on hepatic cholesterol metabolism and the concentration and composition of plasma lipoproteins in the male Syrian hamster.

MATERIALS AND METHODS

After sublethal whole-body 60Co gamma-irradiation (8 Gy, 1 Gy/min), plasma lipoproteins were separated by density-gradient ultracentrifugation. Activities of hydroxymethylglutarylCoA (HMGCoA) reductase and of cholesterol 7alpha-hydroxylase were measured in hepatic microsomes and the low-density lipoprotein (LDL) receptor mass was determined in hepatic total membranes. Lipid peroxidation in LDL was assessed in vitro as the formation of conjugated dienes at 234 nm. A group of pair-fed animals served as controls as the food intake was markedly decreased with exposure to radiation.

RESULTS

Plasma lipid concentrations decreased 2 days post-irradiation and then markedly increased by day 6 post-irradiation; plasma cholesterol was increased by 77% and triglycerides by +207%. LDL accumulated in plasma while high-density lipoprotein (HDL) levels decreased. HDL contained significant amounts of apo SAA, the acute phase apolipoprotein. The activities of hepatic HMGCoA reductase, the rate-limiting enzyme for cholesterol synthesis, increased (+125%, p=0.06); hepatic cholesterol 7alpha-hydroxylase, the rate-limiting enzyme for bile acid synthesis, decreased (-85%); and the hepatic LDL receptor mass also decreased (-44%). The susceptibility of LDL to oxidation was also increased when animals were exposed to radiation.

CONCLUSIONS

Lipoprotein modifications that appeared following radiation exposure may result from an induced inflammatory state and may further contribute to vascular damage.

Prevalence of drugs of abuse in urine of drivers involved in road accidents in France: a collaborative study

The collaborative, anonymous, case-control study was intended to determine the prevalence of opiates, cocaine metabolites, cannabinoids and amphetamines in the urine of drivers injured in road accidents and to compare these values with those of non-accident subjects ("patients") in France. Recruitment was performed nationwide in the emergency departments of five hospitals and comprised 296 "drivers" aged 18 to 35 and 278 non-traumatic "patients" in the same age range. Females represented 28.4% of "drivers" and 44.2% of "patients." Screening for drugs in urine was performed by fluorescence polarization immunoassays in each center. Each positive result was verified using gas chromatography-mass spectrometry (GC-MS), in a single laboratory. Statistical analysis comprised single-step logistic regression and simultaneously took account of confounding factors and the final differences in prevalence values between the two populations or different subgroups. Cannabinoids were found in 13.9% of drivers (16.0% of males and 8.3% of females, p < 0.05) and 7.5% of patients (12.3% of males, 1.6% of females, p < 0.0001); only in females was this prevalence higher in injured drivers than in patients (p < 0.05). Opiates were present in 10.5% of drivers' and 10.4% of patients' urine samples (NS), and were more frequent in urine samples positive for cannabinoids, in drivers (p < 0.01) as well as in patients (p < 0.001). The prevalence of cocaine metabolites in drivers and patients was 1.0 and 1.1% and that of amphetamines 1.4 and 2.5%, respectively. No causal relationship between drugs and accidents should be inferred from this retrospective study. Nevertheless, the high prevalence of cannabis and opiate (licit or illicit) use in young people, whether injured drivers or patients, has potential implications for road traffic safety in France. Cocaine and amphetamines did not appear to be a major problem, unlike the experience in other countries.

Effects of ionizing radiation (neutrons/gamma rays) on plasma lipids and lipoproteins in rats

Male Wistar rats weighing 250 g were exposed to 4 Gy of neutrons/gamma radiation (3.33 Gy of neutrons and 0.66 Gy of gamma rays). After whole-body irradiation, plasma cholesterol and phospholipid levels increased up to 62 and 37%, respectively, at day 4 and then returned to control values 12 days after irradiation. Plasma triglyceride concentrations decreased concomitantly with decreased food intake after irradiation but remained higher than in pair-fed control rats. Plasma lipoproteins were separated by ultracentrifugation on a density gradient (1.006-1.210 g/ml). Four days after irradiation, most of the cholesterol (62% compared to 31% in controls, P < 0.001) is transported by apolipoprotein E-rich high-density lipoproteins. At the same time, plasma levels of apolipoproteins B and E were increased by 28 and 65%, respectively, while those of apolipoproteins AI and AIV were reduced by 21 and 59%, respectively. While in the liver of irradiated rats the apolipoprotein B/E receptor number was not modified, the hydroxymethylglutaryl coenzyme A reductase activity was fivefold higher than in control pair-fed rats. Four days after irradiation, the susceptibility of lipoproteins to peroxidation, as measured by the formation of conjugated dienes in the presence of Cu2+, was markedly increased while plasma vitamin E levels were decreased, demonstrating that irradiation reduces antioxidant stores markedly. These results suggest that such modified lipoproteins could be involved in radiation-induced vascular damage.

Use of the Microwave-Assisted Process in extraction of fat from meat, dairy, and egg products under atmospheric pressure conditions

Fat from meat, dairy, and egg products was extracted by using Microwave-Assisted Process (MAP) technology under atmospheric pressure conditions. Fat content was determined gravimetrically after extraction with microwaves and organic solvents that are transparent to microwaves relative to the sample. (In situ hydrolysis was performed for dairy and egg products.) Fat from the food sample migrated completely to the extractant when samples were irradiated with focused microwave for a total of 3 min for meat products, 1 min for dairy products, and 4 min for egg products. Unlike current methods used for determining fat in meat products, the microwave-assisted method does not require a dry sample, because moisture in the sample (around 75%) enhances the efficiency of extraction. No preprocessing was required for meat samples other than homogenization, which is critical, as it is for other current methods. In addition to speed and ease of use, the features of this technology are low solvent consumption, low energy consumption, reproducibility, and recoveries similar to or even better than those of conventional extraction methods.

Hypocholesterolemic action of beta-cyclodextrin and its effects on cholesterol metabolism in pigs fed a cholesterol-enriched diet

To examine the effects of beta-cyclodextrin (BCD), a non-absorbable carbohydrate, on lipid metabolism, growing pigs were fed a 0.3% cholesterol-enriched diet for 4 weeks or this diet containing 5% or 10% BCD. Pigs fed a basal diet without added cholesterol or BCD were used as controls. The cholesterol-rich diet induced hypercholesterolemia (1.75 vs. 0.84 g/l plasma) due to increased LDL concentration, delayed the plasma clearance of vitamin A, enhanced liver cholesterol storage, lowered the hepatic activities of LDL-receptors (by 47%) and HMG-CoA reductase (by 62%), stimulated cholesterol 7alpha-hydroxylase (x3), and accelerated the fecal output of neutral sterols (x4). Addition of BCD to the cholesterol-rich diet prevented the elevation of plasma cholesterol due to dietary cholesterol excess. Moreover, BCD produced a dose-dependent effect in reducing liver cholesterol storage, stimulating hepatic cholesterogenesis, increasing the proportion of primary bile acids in bile and in feces, and the fecal loss of neutral sterols and bile acids. Pigs receiving 10% BCD thus differed markedly from controls, especially for HMG-CoA reductase and cholesterol 7alpha-hydroxylase hepatic activities (x5), and fecal output of total bile acids (x3) and hyocholic acid (x20), and their overall cholesterol synthesis was higher (+50%), despite the abundant dietary cholesterol. Owing to the property of BCD to bind cholesterol and bile acids in vitro, these results suggest that this resistant carbohydrate accelerates body cholesterol turnover by reducing cholesterol absorption, increasing cholesterol and bile acid synthesis, and altering the action of the intestinal microflora.

Dyslipidemia and diabetes: animal models

Many models of diabetes dyslipidemia are available. Animals with chemically-induced diabetes have been used to study insulin-dependent diabetes. Hypercholesterolemia in streptozotocin-induced diabetes in rats results from increased intestinal absorption and synthesis of cholesterol. Lipoproteins from diabetic rats are oxidized and demonstrate cytotoxicity, a feature which can be prevented by insulin or antioxidant treatment. Diabetic rabbits fed a cholesterol-rich diet do not develop atherosclerotic lesions because accumulated VLDL are apo E-depleted, too large and do not enter into the arterial wall. Models for non-insulin-dependent diabetes (NIDDM) are obtained through selective breeding or dietary conditions. The obese Zucker rat (fa/fa) is characterized by hyperphagy, hyperglycaemia, hyperinsulinemia, insulin-resistance, hypertriglyceridemia and hypercholesteolemia. It responds to dietary, hormonal and drug treatments, but does not develop atherosclerosis spontaneously. It is used as a model for obesity, NIDDM and type IV hyperlipidemia. The JCR:LA cp rat bears the corpulent gene and develops similar characteristics to those of the Zucker rat. However, insulin-resistance is more severe in homozygous males (cp/cp), and cardiovascular lesions are observed. Their appearance is reduced by treatments which decrease hyperinsulinemia and insulin resistance but not by lowering lipid levels alone. The sand rats (Psammomys obesus) develop obesity and NIDDM when fed a laboratory diet. When cholesterol and anti-thyroid drug are added to the diet, they develop cardiovascular lesions. This species constitutes a new model for studying atherosclerosis-related diabetes.

Effect of simvastatin treatment on plasma apolipoproteins and hepatic apolipoprotein mRNA levels in the genetically hypercholesterolemic rat (RICO)

The effects of long-term treatment with simvastatin on plasma lipoproteins, plasma apolipoproteins, and on hepatic apolipoprotein gene expression were evaluated in genetically hypercholesterolemic (RICO) rats. Simvastatin administration caused a decrease in plasma triglyceride and phospholipid concentrations. Plasma cholesterol concentration was not changed by simvastatin, but cholesterol distribution among plasma lipoproteins was altered. Plasma apo B, apo A-I, and apo A-IV concentrations were lowered by simvastatin treatment whereas plasma apo E concentration was not affected by this drug. In the liver, simvastatin treatment induced a significant decrease of apo E mRNA level but had no effect on apo B, apo A-I, and apo A-IV mRNA abundances. It appears that simvastatin may modify plasma apolipoprotein concentrations by influencing their hepatic synthesis at both pre- and posttranscriptional levels.

Effects of plasma lipid levels on blood distribution and pharmacokinetics of cyclosporin A

The present study attempted to characterize the distribution of cyclosporin A (CsA) among the lipoprotein fractions, very-low-, intermediate-, low-, and high-density (VLDL, IDL, LDL, and HDL, respectively) in the plasma of patients awaiting heart transplantation and the influence of plasma lipid constituents on the pharmacokinetics of CsA. Major fractions of a therapeutic concentration of CsA were found in HDL and in LDL. In addition, plasma lipid concentrations (total cholesterol, triglycerides, phospholipids, VLDL-cholesterol--TC, TG, PL, VLDLc, respectively) are positively correlated with the CsA distribution within the LDL fraction, and negatively correlated with the CsA distribution within the HDL fraction. Thus, the percentage of CsA in each type of lipoproteins was shown to vary with the lipid levels among individuals. A significant negative correlation was found between apparent distribution volume at steady state (Vss) in plasma and TC, PL, and LDLc and between the area under the curve measured in blood (AUCB) for whole blood and PL.

Reduction of postprandial lipemia after acute exposure to high altitude hypoxia

The effects of acute exposure to high altitude hypoxia upon plasma levels of lipids and lipoproteins were studied in 6 healthy subjects observed under strict dietary control. Fasting and postprandial values, first measured at low altitude (< 300 m), were compared to values measured 7 days after transfer by helicopter to the Observatoire Vallot (4350 m) near Mont-Blanc. Plasma levels of catecholamines and thyroid hormones were measured in parallel. Under normoxic conditions, a rise in plasma levels of cholesterol, triglycerides and phospholipids was found 4 hr after the test-meal, whereas circulating norepinephrine fell. Under hypoxic conditions, postprandial effects on lipid parameters disappeared, lipemic responses to the test-meal were dramatically reduced and plasma levels of norepinephrine increased. These effects were accompanied by a fall in triglyceride-rich lipoproteins, generally associated with a slight elevation of HDL-cholesterol, especially the less dense HDL2 fraction. When all results obtained in normoxic and hypoxic conditions were analyzed together, a series of highly significant correlations were found between the magnitude of postprandial lipidemia and various lipid parameters, in particular HDL2-cholesterol which was negatively correlated. These observations strongly suggest that high altitude hypoxia, independent of interfering variables such as exercise training or cold exposure, induced a net stimulation of the lipolysis of plasma triglycerides.

Lipid and apolipoprotein changes after orthotopic liver transplantation for end-stage liver diseases

Orthotopic liver transplantation was performed in 37 patients with different endstage liver diseases. Changes in lipid and apolipoprotein concentrations were followed daily from day 1 to 20 after surgery and regularly thereafter until 12 months. When the acute effects of surgery had cleared away, there was a sharp drop in HDL-C, apo A-I and A-II from day 1 to 5, a stabilization at their lowest values from day 5 to 15 and then a progressive rise. Contrasting with this drop, triglycerides, apo B, C-II and C-III increased from day 1 to 5 with variable concentrations thereafter. Apo SAA considerably increased early after surgery and remained significantly higher than normal in most patients after 12 months. All other parameters returned to normal from 3 to 6 months after transplant. The mechanism leading to these lipid and apolipoprotein changes are discussed with respect to the distant effect of infusions, re-alimentation, immunosuppressive therapy and lipoprotein metabolism. The apolipoprotein concentrations appear very useful indicators of functional liver recovery.

Effect of chronic glucagon administration on lipoprotein composition in normally fed, fasted and cholesterol-fed rats

Male adult Wistar rats received daily (at 9 a.m. and 5 p.m.) 10 micrograms of zinc-protamine glucagon by subcutaneous injection for 8 days. Plasma cholesterol levels were decreased by 36% in fed rats, 33% in cholesterol-fed rats and by 55% in fasted rats. Lipoproteins were separated into 22 fractions by ultracentrifugation using a density gradient. Glucagon administration decreased the cholesterol content in all lipoproteins except low density lipoprotein (LDL1) (1.006-1.040) and very low density lipoprotein (VLDL) from cholesterol-fed rats. The main decrease (-57 to -81%) was observed in 1.050-1.100 g/mL lipoproteins (LDL2 and HDL2), which contained a large amount of apo E, while HDL3 cholesterol was not affected. Triacylglycerol levels were decreased only in chylomicrons and VLDL (-70%) of fed and cholesterol-fed rats, while plasma and lipoprotein triacylglycerol levels were not changed in fasted rats treated with glucagon. In normally fed rats glucagon administration increased by 42% the fractional catabolic rate of [125I]HDL2 while the absolute catabolic rate appeared to be unchanged. Glucagon seems to be a potent hypolipidemic agent affecting mainly the apo E-rich lipoproteins. Its chronic administration limits lipoprotein accumulation which occurs upon cholesterol feeding.

Lipolytic activities in rats fed a sucrose-rich diet supplemented with either cystine or cholesterol: relationships with lipoprotein profiles

To study the relationships between lipolytic activities and plasma lipoprotein levels in rats, three diets were given for 8 weeks: a semipurified diet (based on sucrose, casein and lard) and this diet enriched with 5% cystine or with 1% cholesterol. Both supplemented diets induced hypercholesterolemia. Lipoprotein analysis by density gradient ultracentrifugation of plasma indicated that hypercholesterolemia of cystine-fed rats (+52%) was characterized by an increased cholesterol level in high-density lipoprotein (HDL; +131%) and low-density lipoprotein 2 (LDL2; +147%), the lipoprotein fraction containing essentially apolipoprotein-E-rich high-density lipoproteins (HDL1), and was associated with a decreased cholesterol level in triglyceride-rich lipoproteins (TRL: -69%). That obtained by cholesterol feeding (+28%) was due to a large increase in the TRL cholesterol level (+315%) whereas cholesterol was reduced in HDL (-40%) and in LDL2 (-60%). Under these dietary conditions, the activity of hepatic lipase (HL) was measured in liver homogenates and those of both HL and lipoprotein lipase were measured in plasma after heparin injection. The activity of HL (1,783 +/- 132 mU/g liver in control rats) was increased by 48% in cystine-fed rats and decreased by 40% in cholesterol-fed rats. Similar changes were observed in the activity of both lipases measured in postheparin plasma. Highly significant positive correlations linked each lipolytic activity with the level of cholesterol, phospholipids and proteins in LDL2 (HDL1-rich fraction) and in HDL. In contrast, significant negative correlations were found between all of the TRL components and the activity of the lipases.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma lipids, lipoproteins and apolipoproteins in two kindreds of hypobetalipoproteinemia

Plasma lipids and apolipoproteins were quantified in two kindreds of hypobetalipoproteinemia. All affected members were asymptomatic but showed a decrease of 75% in apolipoprotein B and of 69% in LDL-cholesterol. There were no major changes in apo A-I and A-II but all affected family members had reduced levels of apo C-II (by 58%) and C-III (by 59%) without significant decrease in apo C-I and no specific decrease of apo C-III1. Apolipoprotein E is decreased in SDS-PAGE. The plasma level and phenotype of Lp(a) are not affected by HBL, suggesting that a catabolic rather than a synthetic mechanism is responsible for the disease. As shown by density gradient ultracentrifugation, HDL2 particles that contain essentially apolipoprotein A-I, cholesterol and phospholipids represent in affected subjects the major part of HDL. Due to the net reduction of apolipoprotein B-containing particles (VLDL and LDL) as acceptors of lipids in HBL, there is an accumulation of large particles rich in cholesteryl esters.

Effects of chronic glucagon administration on rat lipoprotein composition

Male adult rats of the Wistar strain received daily at 9 a.m. and 5 p.m. 10 micrograms of Zn-protamine glucagon (Novo) for 21 days by subcutaneous injections. Plasma levels of cholesterol, triacylglycerol and phospholipids were decreased by 47, 40 and 21%, respectively. Lipoproteins were separated by sequential ultracentrifugation. Concentrations of cholesterol, phospholipids and proteins were decreased in chylomicrons, VLDL, LDL2 (1.040-1.063 g/ml) and HDL, LDL2 being the most affected by glucagon treatment (-70%). Triacylglycerol levels were decreased only in chylomicrons and VLDL. The relative proportions of cholesterol, triacylglycerol, phospholipids and proteins in lipoproteins were virtually unchanged by glucagon, suggesting a reduced number of some lipoprotein particles in plasma. However, lipoproteins of glucagon-treated rats were depleted in cholesteryl esters, while the proportion of triacylglycerol increased in LDL and HDL. Apo E contents were decreased in plasma, LDL1 (1.006-1.040 g/ml), LDL2 and HDL, whereas apo B100 proportions increased in VLDL and LDL1 in glucagon-treated rats. Glucagon appeared to be a potent hypolipidemic agent affecting mainly the apo-E-rich lipoproteins.

Efficient transformation of Bacillus thuringiensis and B. cereus via electroporation: transformation of acrystalliferous strains with a cloned delta-endotoxin gene

Electroporation was used as a method to transform intact cells of Bacillus thuringiensis and B. cereus. With our optimized method a range of plasmid vectors could be transformed into strains of B. thuringiensis at frequencies of up to 10(7) transformants/micrograms DNA. This high frequency allows cloning experiments to be done directly in B. thuringiensis. A bifunctional vector capable of replicating in Escherichia coli and in Bacillus spp. was constructed. The kurhd1 protoxin gene was cloned into this shuttle vector to produce plasmid pX193, then transformed into B. thuringiensis HD1 cryB and B. cereus 569K. The cloned protoxin gene was expressed in sporulating cultures of both strain HD1 cryB (pX193) and 569K (pXI93), producing crystal protein active in biotests against larvae of Heliothis virescens. This demonstrates the usefulness of the electroporation method for the introduction of cloned toxin genes, in either their native or modified form, into a variety of host strains.

Induction of long-lasting hypercholesterolemia in the rat fed a cystine-enriched diet

The influence of dietary excess (5%) of L-cystine on rat plasma lipoproteins was examined. After only one week of cystine feeding, an increase in the plasma cholesterol level and a decrease in triglyceride levels were observed. The increase in cholesterol level became greater when the duration of cystine-enriched diet increased until eight weeks (+131% after eight weeks), but no further increase occurred between 8 and 20 weeks. This change was essentially due to the progressive increase in cholesterol levels in high density lipoproteins (HDL) and in lipoproteins isolated between 1.040 and 1.063 g/ml, i.e., certain low density lipoproteins (LDL2), and containing mainly apoE-rich lipoproteins (HDL1). The decrease in plasma triglycerides resulted from that of chylomicrons and very low density lipoproteins (VLDL). The effects observed after four or eight weeks of cystine feeding were maintained for eight weeks after replacing the cystine diet by the standard diet. Ingestion of the standard diet containing either cholestyramine (2%) or probucol (0.25%) following eight weeks of cystine feeding significantly decreased plasma cholesterol levels. It is concluded that cystine-fed rats are a useful tool of investigation for understanding mechanisms leading to increased plasma cholesterol level and for hypocholesterolemic drug trials.

Effect of portacaval anastomosis on plasma lipoproteins of lean and obese Zucker rats

The distribution of cholesterol (C), triglycerides (TG), phospholipids (PL) and proteins in the different lipoproteins was studied in lean and obese Zucker rats under 2 conditions: non-operated and after portacaval anastomosis (PCA). All lipoproteins, but mainly the d less than 1.006 g/ml (chylomicrons + VLDL) fraction, were increased in obese rats. They were hypertriglyceridemic (+ 675%) and hypercholesterolemic (+ 207%). PCA decreased cholesterolemia by about 50% and triglyceridemia by 50-70% in both lean and obese rats. Except for VLDL, enriched in TG in obese rats, proportions of C, TG, PL and proteins in lipoproteins were about the same in obese and lean Zucker rats and were nearly unchanged by PCA, suggesting an increased number of particles in obese rats and a decreased number after PCA. Lipoproteins of obese rats were enriched in apo C and proportions of apo E and apo B were decreased in the d less than 1.006 g/ml fraction. PCA decreased the proportion of apo C in all lipoproteins.

Cholesterol metabolism in lean and obese Zucker rats: effects of portacaval anastomosis

The effects of portacaval anastomosis (PCA) on cholesterol biodynamics of male adult (fa/fa) Zucker rats and their lean littermates were studied with an isotopic equilibrium method. Animals were fed with a sucrose-rich semi-purified diet. Obese rats were hypercholesterolemic (2.03 +/- 0.14 vs 1.06 +/- 0.7 mg/ml), had a cholesterol-enriched liver (135.3 +/- 14.5 vs 40.0 +/- 2.6 mg/liver) and accumulated cholesterol in body pools. However no difference in the rates of cholesterol absorption, synthesis, fecal elimination or transformation into bile acids distinguished obese from lean Zucker rats. In both lean and obese rats, PCA decreased cholesterolemia by about 28 per cent and liver weight by 40 per cent while the total cholesterol content of the liver was not affected. Input of synthesized cholesterol (internal secretion) was strikingly decreased by the shunt (from 13.2 +/- 0.6 and 12.6 +/- 0.7 mg/day/rat before PCA, to 8.9 +/- 0.8 and 8.6 +/- 1.0 mg/day/rat after PCA) in lean and obese rats respectively. A similar decrease was observed in the cholesterol transformation into bile acids. Since the activity of the gut for cholesterol synthesis, as shown by the fecal external secretion (cholesterol synthesized by the gut and directly eliminated in the gut and feces) was probably not modified, the reduction of internal secretion induced by PCA resulted from decreased hepatic cholesterogenesis. It is suggested that this decrease may be one of the factors involved in the lowering effect of PCA on plasma cholesterol level.

[Massive traumatic hemoptysis]

A case is reported of a patient who suffered a rupture of one lung as result of thoracic trauma. This gave rise to respiratory distress with massive haemoptysis which was initially treated with a double-lumen endotracheal tube, with separate lung ventilation, a chest drain and massive transfusion. A haemostatic pneumonectomy had to be performed because of the persisting and profuse bleeding.

[Effect of short- or medium-chain fatty acids on cholesterol dynamics in the rat]

The effects of a diet consisting of 10% medium-chain triglycerides (C8:0, C10:0) or 10% homogeneous triglycerides of 6- to 14-carbon chain saturated fatty acids on cholesterol turnover processes were studied in rats using the isotope equilibrium method. Cholesterol absorption was not significantly affected by the type of dietary fatty acid ingested. In contrast, lengthening of the fatty acid chain caused a moderate increase in the rates of cholesterol secretion (internal and external) and of transformation into bile acids. Thus, cholesterol synthesis was 80% higher in rats fed trimyristin (25.7 mg/day) than in those receiving tricaproin (14.6 mg/day). This increase seems essentially due to stimulated liver cholesterogenesis, as shown by in vivo incorporation of 14C-acetate.

Factors determining to biotransformation of cholesterol to bile acids in the rat: development of a new model

This paper proposes a model for cholesterol metabolism in the rat based on extensive data obtained on rats in isotopic equilibrium with radioactive cholesterol. These data reveal that the rate of bile acid synthesis is closely related to cholesterol input. Hence the transformation of cholesterol into bile acids is conceived as a determinative process for the dynamics of the cholesterol system in the rat. This process is not per se regulated if the definition of regulation is as follows: to maintain constant a variable. In fact, the control of the transformation is dependent on the particulate transport of the plasma lipoproteins into the liver. In other words, from a physiological point of view, the process governing the net removal of cholesterol from the plasma into the liver is the limiting step for the cholesterol transformation into bile acids. Temporary losses or gains of cholesterol by the system modify the flow of the cholesterol transformation into bile acids during a transitory period. The effect of the exogenous taurocholate is so interpreted. Because this bile acid seems to act initially on the capacity of the liver to esterify free cholesterol, there results a loss of cholesterol which cannot be transformed into bile acids.

Diet and sterol biohydrogenation in the rat: occurrence of epicoprostanol

The fecal sterols from rats fed several types of semipurified or commercial diets were analyzed by a combination of thin layer and gas liquid chromatography. In rats fed semipurified diets with lard, sucrose, and casein, increasing proportions of lard (0, 8, 20, 65%) enhanced the fecal coprostanol/coprostanol + cholesterol ratio (from 0.50 to 0.85). This ratio was reduced by replacing lard with triolein or a mixture of calcium oleate and linoleate (1:1) and did not change when trierucin was substituted. No coprostanol formation was observed in rats fed a diet with tripalmitin or tristearin. The addition of sodium hyodeoxycholate (0.5%) or cholestyramine (2%) to the basal diet was without effect on the coprostanol/coprostanol + cholesterol ratio in the feces. The addition of sodium taurocholate (0.2, 0.75, and 4%) strongly reduced coprostanol formation, while a chronic bile duct ligation led to an enhancement. Cholesterol feeding (0.05, 0.2, and 0.5% in the diet) slightly increased (from 51 to 66%) coprostanol formation. Trace amounts of epicoprostanol were generally found in the feces. However, in some cases a very high proportion (up to 60%) of this sterol was observed. Possible relationships between the presence of epicoprostanol and the nature of the diet are discussed.

Effects of dietary fiber and salt mixtures on the cholesterol metabolism of rats

The isotopic dilution method, which permits the in vivo measurements of the rates of the processes involved in cholesterol turnover, has been applied to rats fed a commercial stock diet or a basal semipurified diet in which either the nature and proportions of the source of dietary fiber or the salt mixture were changed. The cholesterolemia was about 100 mg/100 g in rats fed agar-agar, cellulose, bran or the stock diet. Pectin addition (5%) lowered significantly the plasma concentration of cholesterol (70 mg/100 g). Changes in the source of dietary fiber or salt mixture have moderate effects on the absorption coefficient of dietary cholesterol (range 58.2%-82%). In comparison to agar-agar, cellulose at 2.3% in the diet significantly lowered this coefficient, but larger amounts of cellulose (6.8% or 12.3%), or pectin (5%) were without effect, while bran addition (10%) tended to slightly decrease cholesterol absorption. Hence, high levels of cellulose in the diet increased the absorption coefficient in comparison to a low cellulose diet. A decrease of this coefficient was also observed when the calcium content of the diet was increased. Cholesterol biosynthesis and fecal excretion were inversely correlated to the absorption coefficient of dietary cholesterol in rats fed all of the semipurified diets indicating, as previously shown, that the intestine was the major source of biosynthesized cholesterol diverted into the plasma. However, feeding a commercial stock diet greatly increased the cholesterogenesis and the fecal elimination of bile acids, suggesting a high hepatic cholesterogenesis.